Dovetail Spacing Calculator
Evenly spaced dovetails look right and are easier to cut consistently. This calculator divides a board width into equal tails separated by pins, starting and ending with a half pin at each edge as tradition dictates. Enter the board width, how many tails you want, and your pin width at the baseline, plus a slope ratio, and it returns the tail width, the center of each tail, and the slope angle for your bevel gauge. The layout math is exact; pin and tail proportions are your stylistic choice, so they are editable inputs.
Dovetail layout formula
Pins total = tails + 1 (two half pins at edges)
Pin material = tails * pin width (full pins count twice as halves)
Tail width = (board width - tails * pin width) / tails
Tail center spacing = board width / tails
Slope angle = atan(1 / ratio)
This assumes a half pin at each edge and equal full pins between tails, so the total pin material equals the tail count times the pin width. The remaining width splits evenly among the tails.
Dovetail layout tips
- 1:8 slope (about 7.1 degrees) suits hardwoods; 1:6 (about 9.5 degrees) suits softwoods.
- Always begin and end with a half pin at the edges for strong corners.
- Mark pins directly from cut tails for a guaranteed match.
- Wider tails and narrow pins give a refined hand-cut look.
- Keep your saw to the waste side of every line consistently.
Dovetail spacing: frequently asked questions
How do I lay out evenly spaced dovetails?
Subtract the two half-pins at the edges and the full pins between tails from the board width, then divide the remaining width equally among the tails. The repeating unit is one tail plus one pin, so spacing the layout cleanly means choosing a tail count that divides the usable width into equal pieces.
What is a good dovetail slope or ratio?
Common slopes are 1:6 for softwoods and 1:8 for hardwoods, expressed as rise over run. A 1:8 slope is about 7.1 degrees from vertical; 1:6 is about 9.5 degrees. The calculator reports the angle for the ratio you enter so you can set a bevel gauge or marking template.
Should I start with a half pin at each edge?
Yes, traditional through and half-blind dovetails begin and end with a half pin at the board edges. This puts long-grain glue surface at the vulnerable corners and looks balanced. This calculator assumes a half pin at each edge.
How wide should pins be?
Pin width is a matter of style and strength. Machine-cut joints often have pins and tails of similar size, while hand-cut work frequently uses narrow pins for a refined look. Enter your chosen pin width at the narrow (baseline) face and the calculator spaces the tails to fit.
Does this give the tail width or the pin width?
It returns the tail width measured between pins at the baseline, the center positions of each tail, and the slope angle. You mark the pins from the tails (or vice versa) so the mating parts match exactly, which is the reliable way to get a tight fit.
Official sources
- NIST Digital Library of Mathematical Functions: DLMF, trigonometric functions.
- USDA Forest Products Laboratory: Wood Handbook, joint and gluing guidance.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.